Pointer-controlled, periodic circuit breaker



Jan. 27, 1948. K. H. BLOMBERG 2,435,027

POINTER-CONTROLLED, PE-RIODIC cmouxf BREAKER Filed Oct. 21, 1942 2Sheets-Sheet 1 Fig. 2

INVENTOR L2 BY K.H.BLOP1BERG AT Tm}.

Jan. 27, 1948. K. H. BLOMBERG 2,435,027

POINTER-CONTROLLED, PERIODIC CIRCUIT BREAKER Filed on. 21, 1942 2Sheets-Sheet 2 Fig. 3

INVENTOR Bx K-H-BLQMBERCT "qwasw q WW! Patented Jan. 27, 1948POINTER-CONTROLLED, PERIODIC CIRCUIT BREAKER Knut Hugo Blomberg,Appelviken, Sweden, as-

sig'nor to Telefonaktiebolaget L. M. Ericsson, Stockholm, Sweden, acompany of Sweden Application October 21, 1942, Serial No. 462,868 InSweden October 21, 1941 2 Claims. (01. 175-373) The present inventionrelates to an automatic electric arrangement for control of a circuit independence upon the position of a pointer in a measuring instrument.Such arrangements are used among other things forthe control of thetemperature in electric furnaces. The object of the invention is toproduce a controlling apparatus of such a type that is simple and cheapand in which'the pointer of the measuring instrument is not exposed tomechanical stresses.

The invention will be more closely described with reference to theaccompanying drawings in which Fig. 1 is a perspective view of a deviceaccording to the invention, Fig. 2 is a circuit diagram, Figs. 3 and 4show the contact spring assembly with the springs in differentpositions.

On a pivot l is placed a U-shaped arm 2 which I at the one end supportsa relay 3 and at the other is formed as a pointer 4 that is movable overa scale 5. The arm 2 is adjustable in different positions by turninground the pivot I which turning is produced by the wheel I actuating atoothed gear segment 6. The measuring instrument 8 is arranged in such away that the axis of driving axle 9 of the pointer coincides with theaxis of the pivot l. The pointer axle supports the pointer In, theprolongation H of which cooperates with one, l5, of the two springassemblies I4 and i5 of the relay 3. The contacts Na and Nb of thespring assembly I4 are closed when the relay is in its rest position butare opened when the armature l6 of the relay is attracted by a stud onthe armature lifting spring llb. The spring assembly IS, theconstruction of which appears from the Figs. 1, 3 and 4, comprises twocontact springs l9 and 28. The latter is furnished with a reinforcement21 and studs l8 and 22. The-spring I9 is provided with a stud 28. Abovethe contact is arranged a stationary bridge 2'! provided with a track 32adapted, at times. to receive the stud 28. When the armature I8 isattracted and presses the stud II the springs 28 and I9 are lifted, thelatter by meansof the stud 22. A closing of the contact between thesesprings cannot occur if the movement upwards of the spring I9 is notlimited. This closing is however effected in the position shown in Figs.3 and 4 when the pointer prolongation ll takes such a position that itlies across and obstructs the track 32. When the two springs l8 and arethen lifted, the stud 28 of the spring is can not penetrate into thetrack 32. The movement upwards of the spring lfl' will therefore bestopped as soon as the stud 28 engages the prolongation I l. During thecontinued movement of the armature only the spring 20 will be liftedupwards and. in so doing it makes contact with the spring l9 as shown inFig. 4. If the prolongation H assumes a position laterally of the springassembly as shown in Fig. 1

with dotted lines, the track 32 will be open and:

the stud 28 will pushinto the track when the springs are being lifted.The two springs will then be lifted parallel to each other during thewhole movement of the armature and there will be no contact betweenthem. In order to prevent the stud 28 from striking and pressing hardagainst the pointer if the pointer prolongation H is just in front ofthe track 32 there is a spring 25, Fig. 3, which is furnished with astud 24. The spring is bent at its free end in such a way that a surface28 facing the pointer prolongation is obtained. The spring is alsofurnished with a flap 26 for limiting the movements of the pointer inone direction, Fig. 1. n opening 3|, Fig. 1, is arranged in the samespring 25 in such a way that the stud 28 is able to move freely therein.When the contact springs 18, 28 are beinglifted at the movements of thearmaturethe'spring- 25.will also be lifted upwards by the studs 22 andstud 24. The surface 29 then will make .contact'with the pointerprolongation H.

' During: the "continued movement upwardsof the armature the, free endof the. spring 25 will be bent adj'acentfthe stud 24 in such a way thatit bears yieldably against 'the prolongation H as is shown in landpresses the prolongation ll elastically'against-the bridge 21 before thestud 28 strikes against the-same. 1 g

Fig. 2 is a circuit diagram showing the inven' tion being applied to, anarrangement controlling the temperature in a furnace. M is ameasuringinstrument. Both its terminals Tl are connected to a thermocouple in thefurnace over the resistance R5. The mercury circuit breaker H isconnected to a control circuitover the line T2, which circuit supervisesthe connectionanddisconnection of a'heater in the furnace. This heaterwill be connected when the circuit breaker. H takes the position shownin Fig. .2. The relay 3 is connected to the wires (1, b, over' the glowlamp G, the resistance R4 and the rectifier L2. The wires a, b areconnected with an alternating current source. KI and K2 are condensers.The relay 3 is energized periodically in knownlmanner by means of theglow lamp G'and the condenser cult of the slow release relay R. Everytime the relay I is energized the contact between the springs Ila andIlb in the spring assembly ll of the relay will be broken and the twosprings II and 20 will be lifted. In dependence upon the position of thepointer prolongation I I, the contact between I9 and 20 then will bebroken or closed. If the pointer II is just in front of IS and 20, thisimplies that the right temperature in the furnace is obtained. As thistemperature must not be exceeded the contact I9, 20 will be closed atthe next momentary attraction of the relay R, whereby the slow releaserelay is ener gized and closes a holding circuit for itself overcontacts r1, r2. After de-energization of the relay, said holdingcircuit is closed over the contact Ha, Mb. On attraction of the relay Rthe circuit breaker H will be operated, whereby the above describedheater in the furnace will be disconnected. The heater will continue tobe disconnected for as long a time as the temperature is at the value,which corresponds to the position of the pointer I I right in front ofthe springs I9, 20. In this position of the pointer the relay R, isenergized. The relay R. will be energized also during the periodicalenergization of the relay 3 as the contact I9, 20 at every energizationof the relay 3 will be closed at the same time as the contact Ila, Mbwill be broken. If the temperature falls and the pointer thus will takesuch a position that it cannot co-operate with the springs I9, 20 thecontact I9, 20 will not be closed at the next energization of the relay3. Said contact remains broken and at the same time also the contact Ha,Ilb is being broken. The circuit of the relay R will therefore be brokenand relay R, de-energized whereby the contact rI, r2 will be broken andthe circuit breaker H restored to its rest position in which the heateris again connected. The temperature increases thereby again to a valuecorresponding to the pointer II coming right in front of the springs I9,20 whereby the heater will then be disconnected as above described. Itis evident that the heater will be alternately connected anddisconnected. the temperature through the arrangement being thusmaintained at a constant value.

I claim:

1. An automatic electric arrangement for the control of a circuit independence upon the position of a pointer movable over a scale of ameasuring instrument comprising a contact spring assembly disposed inthe path of movement of and controlled by said pointer, said assemblyincluding contact springs for controlling said circuit, means forselectively setting said assembly along the path of movement of saidpointer, a second circuit including a discharge tube and a condenser,and a relay periodically energized by said second circuit for operatingthe springs of the spring assembly in dependence upon the position ofsaid pointer.

2. An arrangement as claimed in claim 1, wherein said second circuitalso includes a variable resistance.

' KNUT HUGO BLOMBERG.

REFERENCES CITED The following references are of record in the file'ofthis patent:

UNITED STATES PATENTS Number Name Date 2,101,452 Rauch Dec. 7, 19372,129,747 Sorensen Sept. 13, 1938 2,201,031 Eichelberg May 14, 19402,249,368 Weckerly July 15, 1941 2,249,369 Williams July 15, 1941

